This discourse relates to a casting system, and more particularly to a core assembly that may be employed in a casting system to manufacture a part.
Gas turbine engines are widely used in aircraft propulsion, electric power generation, shift propulsion and pumps. Many gas turbine engine components are cast components. One example casting process is known as investment casting. Investment casting can form metallic parts having relatively complex geometries, such as gas turbine engine parts requiring internal cooling passageways. Blades and vanes are examples of such parts.
The investment casting process typically utilizes a casting system that includes a mold having one or more mold cavities that define a shape generally corresponding to the part to be cast. A wax or ceramic pattern of the part is formed by molding wax or injecting ceramic material around a core assembly of the casting system. A shell is formed around the core assembly in a shelling process to assemble the casting system. The shell is fired to form the casting system including the shell having one or more part defining compartments that include the core assembly. Molten material is communicated into the casting system to cast the part. The shell and core assembly are removed once the molten material cools and solidifies.
Maintaining wall thicknesses to specification during the casting process can be difficult because of the relatively thin-walled constructions of parts that are cast to include relatively complex internal cooling passageways. The spacing between the core assembly and the surrounding shell is one area that must be controlled to maintain wall thicknesses during the casting process.